Ion Beam Etching Substrate Rotation for Fine Pattern Redeposition
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Solution Overview
Problem
Ion beam etching techniques struggle to effectively process fine patterns in semiconductor memory devices due to redeposition of etched materials on side walls, especially when using oblique ion beam incidence, which shadows the bottom portions of pattern trenches and hinders efficient etching.
Innovation Solution
An ion beam processing method and apparatus where the substrate is tilted and rotated in-plane during ion beam etching, with controlled rotational speed and tilt angle to enhance exposure of the ion beam to pattern trenches, ensuring a larger etching amount from the extending direction of pattern trenches compared to other directions, thereby inhibiting redeposition of films on the bottom portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ion beam etching is performed with substrate tilted to oblique incidence, then redeposited films on side walls can be removed, but the bottom portions of pattern trenches are shadowed and etching becomes difficult
Solution Approach 1:
The substrate is rotated during ion beam etching to dynamically change the incident angle of the ion beam. This rotation allows the ion beam to alternately strike the side walls and bottom portions of the pattern trenches, preventing shadowing while removing redeposited films. The dynamic adjustment of substrate orientation resolves the contradiction between side wall cleaning and bottom etching accessibility.
Solution Approach 2:
The invention introduces rotational movement in the in-plane direction, adding a temporal dimension to the static tilted substrate configuration. By rotating the substrate around its normal axis during etching, the system achieves multi-directional ion beam exposure, allowing both side wall redeposition removal and bottom portion etching to occur sequentially throughout the rotation cycle.
2Manufacturing precision
If ion beam etching is performed on fine patterns, then recording density is improved, but redeposited films accumulate on bottom portions of trenches
Solution Approach 1:
Rotating the substrate during ion beam etching of fine patterns ensures that the ion beam continuously sweeps across the trench bottom surfaces. This dynamic exposure prevents redeposited material from accumulating on the bottom portions by mechanically removing it through ion bombardment, while maintaining the fine pattern dimensions required for high recording density.
Solution Approach 2:
The continuous rotation of the substrate during etching ensures uninterrupted ion beam exposure to all surfaces including the bottom portions of trenches. This continuous action prevents redeposition accumulation by constantly removing redeposited material, maintaining the effectiveness of fine pattern processing throughout the entire etching process.
3Stability of the object's composition
If substrate rotation speed is increased, then uniformity of etching is improved, but etching amount from extending direction of trenches decreases
Solution Approach 1:
The system optimizes the substrate rotation speed parameter to achieve the desired balance between etching uniformity and etching amount. By carefully selecting and adjusting the rotation speed, the process ensures sufficient ion beam exposure time to all surfaces for uniformity while maintaining adequate total ion beam dosage for sufficient etching depth in the trench extending directions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for effective processing of fine patterns by ensuring uniform etching and preventing redeposition of films on the bottom portions of trenches, improving the precision and efficiency of ion beam etching for next-generation memory devices like MRAM and RRAM.
Implementation Method 1
forms plasma by inputting power to an electric discharge unit
Implementation Method 2
forms an ion beam by extracting ions from the plasma with application of a voltage to a grid
Implementation Method 3
The ion beam is made incident on a substrate, and mainly-physically etches a material on the substrate
Data Source
AI summary
The present invention has an objective to provide a processing method and an ion beam processing apparatus capable of inhibiting deposition of redeposited films even for fine patterns. In an embodiment of the present invention, ion beam processing is performed such that an etching amount of an ion beam incident in extending directions of pattern trenches formed on a substrate is made larger than the etching amount of the ion beam incident in other directions. This processing enables fine patterns to be processed while inhibiting redeposited films from being deposited on the bottom portions of the trenches of the fine patterns.